Submarine craft, such as torpedoes, probes and remote-controlled submarines, comprise a tubular casing elongated along a longitudinal axis and designed to move under the thrust of a propulsion system housed in a rear potion of the casing and powered by a source of electrical energy, also housed inside the casing.
The source of electrical energy is typically provided by an electrochemical battery that is capable of supplying high currents to provide an opportune power supply for the electric motors that power the craft.
In particular, electrochemical batteries (for example, see patent application PCT WO2005/053068, which describes an electrochemical battery) comprise:                a main electric battery of the electrochemical type, in which a casing defines a main chamber containing a dry electrolyte (for example, sodium hydroxide or potassium hydroxide) and is provided with means for the controlled admission of a flow of water from the underwater environment, to form a liquid electrolyte upon operation a water admission control, and means for discharging effluent into the underwater environment, typically gases produced by the chemical reaction of the main battery; the main chamber houses a liquid electrolyte recirculation system (using an electric pump) feeding a plurality of electrochemical cells housed in the main chamber;        an auxiliary electric battery that can be activated by remote control for opening the means of controlled admission and supplying power to the electric pump in order to achieve the formation and recirculation of the electrolyte.        
The recirculation system commonly comprises a thermostatic mixer valve that enables adjusting the flow of the liquid electrolyte supplied to the electrochemical cells in order to keep the temperature of the electrolyte equal to a target value. This thermostatic valve, generally three-way, has a first inlet that receives electrolyte directly front the main chamber, a second inlet that communicates with the outlet of a heat exchanger to which the electrolyte present in the main chamber is fed and an outlet communicating with an inlet of the electrochemical cells.
In known electrochemical batteries, such as those described patent application PCT WO2005/053068, the loading of the dry powdered electrolyte is carried out during the assembly of the parts that delimit the main chamber.
However, in many operating situations it would be convenient and/or advantageous to load the dry powdered electrolyte in a subsequent assembly phase of the craft.
The need is therefore felt to provide an apparatus that enables loading the dry electrolyte inside the main chamber.